Oftentimes in pneumatic conveying systems, plural storage bins are provided for different dry, powdered, and/or granular products. It is desired to convey a selected product in one of the bins to a selected one of numerous desired destinations, such as a sealed vessel from which conveyed product can be continuously or intermittently discharged. One type of sealed vessel is a vacuum receiver, an example of which is illustrated in U.S. Pat. No. 4,583,885. The disclosure in U.S. Pat. No. 4,583,885 is to be incorporated herein by reference. It is to be noted that the disclosure in U.S. Pat. No. 4,583,885 draws the product from a conventional gaylord material source. When plural and different storage bins for product is incorporated into a system, a material flow management system is required in order to assure that the proper product in one of the bins is distributed to the proper desired destination and still allow the conveying system to be purged. One type of system which has structure therein for facilitating a purge is disclosed in U.S. Pat. No. 5,340,241, and which is assigned to the same assignee as is the present invention. The disclosure in the aforementioned U.S. Pat. No. 5,340,241 is to be incorporated herein by reference.